1. Field of the Invention
This is related to a patent of invention for an improvement in a lid-seal for a metal containers for a powdered foodstuff or other material, the development of which has as a purpose to develop a lid-seal which assures the necessary tightness, the consequent quality of the packaged product, and the conviction that there will be no possibility of harming the fingers, upon its opening.
2. Related Art
Several types of foodstuff are known which, in order to increase their useful life, allow the use of a process for the elimination of water from their composition, so that they may be converted into powder, such as powdered milk and other products, avoiding the contact with aerobic bacteria, and may, many times, be kept at room temperature for several years. Their packaging material is many times made out of tinned iron sheet which is cut, calendered and welded, with the bottom being sealed by a beaded disc of the same material, sealed with an aluminum sheet together with a ring which serves as a pressure lead, known as “Easy-open,” with said seal allowing the foodstuff to be totally sealed, and opened only for final consumption.
The above mentioned cylinder shaped metal packaging and respective seals are used in a process well known for decades which is used by different manufacturers of powdered milk, milk products, chocolate flavors, and others products.
Some manufacturers use a cylindrical packaging material made out of semi-rigid plastic material which, after the introduction of the product within it, receives an aluminum laminated seal which is hot sealed, receiving a flexible plastic material secondary cover or over-lid, fitted under pressure which, after taking the seal off, shall be used as the lid of the package, a cheaper solution than the one previously mentioned. The problem is in the possibility of the welding used for sealing not being perfect, allowing the entering of aerobic bacteria which could affect the quality of the product.